From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 795B03858C78; Tue, 15 Feb 2022 00:53:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 795B03858C78
From: "nickhuang99 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/104537] New: ICE when generic-lambda as function parameter
 fails to be converted to pointer to function
Date: Tue, 15 Feb 2022 00:53:46 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: nickhuang99 at hotmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-104537-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Tue, 15 Feb 2022 00:53:46 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104537

            Bug ID: 104537
           Summary: ICE when generic-lambda as function parameter fails to
                    be converted to pointer to function
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nickhuang99 at hotmail dot com
  Target Milestone: ---

Consider this invalid conversion for this generic-lambda to pointer to func=
tion
which is defined by "decltype(+[](T&& t )->T{return t+1;}".
This ICE happens when original accepted parameter type changed from "T" to
"T&&".
See compiler explorer (https://www.godbolt.org/z/fde1bc3zE)

I suspect this is some related issue with another unconfirmed case PR104358.

template<typename T>
auto foo(T&& t, decltype(+[](T&& t )->T{return t+1;}) lam){
        return lam(t);
}
void test(){
        foo<int>(5, [](int t){return t+1;});
}


<source>:8:21: error: invalid user-defined conversion from
'test()::<lambda(int)>' to 'int (*)(int&&)' [-fpermissive]
    8 |         foo<int>(5, [](int t){return t+1;});
      |                     ^~~~~~~~~~~~~~~~~~~~~~
...
internal compiler error: error reporting routines re-entered.
0x2174365 warning_at(unsigned int, int, char const*, ...)
...=